Such an elevating mechanism is known from U.S. Pat. No. 3,711,054. The cylindrical outer surface of the housing of the gas spring is directly guided in a guide sleeve connected to the guide tube. The gas spring is not only a supporting and length-adjustable element of a chair or table column, but also a leading and a pivoting element. Since the piston rod is attached to the bottom plate of the guide tube not only freely pivoting, but also with sufficient radial play, the gas spring can adjust to any possible change in stress direction of the seat or the table top, respectively, so that, on the whole, there is little risk of bracing in the guide sleeve. In another elevating mechanism according to the preamble of claim 1, the housing of the gas spring is surrounded by an additional tube, in which the housing of the gas spring is arranged axially unslidable. In this case the additional tube is guided pivotably and longitudinally slidable in the guide sleeve (European Patent No. 0 133 524 corresponding to Japanese utility model No. 60-54446 and U.S. Application Ser. No. 756,844, appeal pending).
The known embodiments have one-piece guide sleeves consisting of high-quality wear-resistant material. They are pressed into the guide tubes. Subsequently the guide surface of the sleeve serving as a slide surface is adapted to the precise dimensions by turning or rubbing. This is necessary because, due to their size, the guide sleeves have wide tolerances and because they are deformed differently when they are pressed into the guide tube. This treatment is expensive. Furthermore, the demands on the guide sleeve to have good sliding qualities, of being resistant to wear and still to offer the possibility to be pressed into the guide tube with corresponding hard-elastic deformation, are very difficult to be realized altogether in terms of material.
From German utility model No. 72 35 759 it is known for an elevating mechanism for the continuous adjustment of chair seats to guide a gas spring in two guide sleeves spaced apart, each of which is provided with support and guide surfaces. The two guide sleeves are pressed into a guide tube and held spaced apart by a distance tube. A special effect of this is not given in German utility model No. 72 35 759.